Little is known about how maternal sleep disturbances in the postpartum period affect mother-infant interaction. The study was designed to assess if less maternal sleep disturbance and less fatigue were associated with more positive mother-child interaction, independent of maternal depression symptoms. Twenty-three mothers completed 1 week of actigraphy and self-report measures of fatigue and depression symptoms. To determine the quality of mother-infant interaction, mothers and infants were then observed in a structured, video-recorded teaching episode. Greater maternal napping frequency was associated with better cognitive growth fostering of the infant (r(s) = .44, p < .05), a subscale of the interaction assessment. Maternal napping, not the quality or quantity of nocturnal sleep, appears to be associated with improvements in mother-infant interactions.